Arnold is promising nothing, except to bring the national GOP to the Left. For the good of all of us in other states, he should be opposed.
And if that is worse for California (I don't think it really is, since Arnold is apparently pro-amnestyon top of everything else), it's YOUR fault for electing Davis in the first place.
He's promising that he will try his best to fix California. Given Arnold's record of doing a world class job on everything he sets his sights on (i.e. bodybuilding, business, acting), I'm inclined to trust him.
McClintock's platform is unworkable promises + an inability to lead. If he hypothetically wins the election, he will go down in history as the governor of California that managed to do worse than Davis.